A water proportioning device for steam irons of the type initially referred to is known from EP-B-0 014 643. In this known device, the valve member of the first valve is comprised of an annular member of an elastomer material having on its inner wall a substantially radial, flexible lip providing the boundary for the valve opening. The valve pin is movable relative to the valve member only axially, providing three different positions in which the valve pin is adapted to be locked in place by means of a snap-in locking mechanism.
In one end position, the two ends of the longitudinal groove are on the same side of the valve opening, the valve pin then closing the valve opening. In a mid-position and in a second end position, the two ends of the longitudinal groove are on either side of the valve opening, with the area of cross-section of the longitudinal groove that lies within the lip defining the amount of water supplied to the steam-generating chamber. The longitudinal groove being correspondingly configured, this cross-sectional area differs in dimension in the two positions, that is, the mid-position and the second end position, enabling a larger or smaller amount of steam to be produced depending on the position selected. The capability of producing a surge of steam does not exist.
Further, from FR-B-2 337 780 a water proportioning device for steam irons is known in which the first valve is opened by turning the valve pin such that, in accordance with its open position, one or several bores provided on the valve pin engage a radial opening provided on the valve member, thus enabling metered amounts of water to be conducted from the water reservoir through the bores into a longitudinal bore disposed on the valve pin and onwards into the steam-generating chamber. In view of their relatively small diameters, the bores provided on the valve pin tend to clog easily by contaminants--the provision of substantially larger bores being close to impossible in view of the thickness of the valve pin. An infinitely variable flow control of the first valve is hardly possible.